Control Panel Wiring Color Code (IEC 60204-1 and NFPA 79)
The recommended wire colours inside control panels and machinery, so power, AC control, DC control and interlock circuits can be identified at a glance.
Panel wiring colours
| Colour | Use |
|---|---|
| Black | AC and DC power circuits |
| Red | AC control circuits |
| Blue | DC control circuits |
| Orange | Interlock circuits supplied from an external source |
| Light blue | Neutral conductor |
| Green/Yellow | Protective earth (PE) |
Why Panel Wiring Colours Matter
Consistent colours let a technician tell, without tracing, whether a wire carries mains power, 230 V AC control, 24 V DC control or a circuit that stays live when the panel isolator is off.
Instrument panels commonly use blue for 24 V DC and a separate colour, or marked ferrules, for 0 V. Intrinsically safe circuits are usually light blue and segregated.
Frequently Asked Questions
What colour is 24 V DC control wiring?
Blue is recommended by IEC 60204-1 and NFPA 79 for DC control circuits.
What colour is AC control wiring?
Red in both IEC 60204-1 and NFPA 79.
Why are some panel wires orange?
They are interlock or control circuits supplied from an external source that remain live when the panel main switch is off.
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